Laser engraving on uneven surfaces – Complete Guide

Using a laser engraver to make intricate patterns is as easy as focusing your laser beam on your material of choice and letting the machine do the rest. But things can get pretty complicated when dealing with a material that is uneven like say, a mug, a wine bottle, or some other cylindrical item.

Laser engraving on uneven surfaces

How do you laser engrave on uneven surfaces?

There are 4 main ways of laser engraving on uneven surfaces. You can use geometrical modeling, a spring-loaded tool, the G-code ripper application or a 3-axis laser engraver. Of these four methods, using a 3-axis laser engraver is the easiest and most efficient method.

Lets have a look at each of these methods in more detail below.

Using geometrical modelling

Geometrical modelling

Geometrical modeling is also known as 3D computer-aided design (CAD) modeling and it is typically used in engineering for representing real-life items as models. Usually, the system elements that are represented in the model must correspond with the components that are on the geometric model.

CAD models are very versatile in that they can capture very fine details including the properties of the materials, the curvatures, etc.  

The 3D nature of CAD software will allow for an accurate representation of the curvatures on your laser engraving material. The main challenge with this solution is that you will have to get a perfect CAD model of your material. If you can manage to get the design right, your project is as good as done. There are lots of Computer-Aided Design software that you can use for your laser engraving projects. Here is a list of the most popular ones;

  • AutoCAD
  • CATIA
  • BobCAD
  • BobCAM
  • Mastercam
  • Inventor
  • Creo
  • Fusion 360
  • Draftsight
  • TurboCAD
  • Rhinoceros
  • Solidworks
  • SketchUp

Using a spring-loaded tool

Using a spring-loaded tool is an easier and faster way of engraving uneven surfaces. The spring-loaded tool makes engraving, marking, etching, and scribing of curved materials easier and more accurate. The tool was specially designed to take into account the variations that are typical of an uneven surface.

A spring-loaded tool works with all CNC engravers or any other machine that uses a 3/16-inch dia tool bit. The tool works by providing constant pressure on the engraving tool bit and this makes it possible to float within the tool holder which helps to compensate for the uneven surfaces.

Using G-Code ripper

G-Code ripper is a little-known but very powerful software written in the Python programming language. The program is open source and so you can easily test it with your engraver without any cost. You can download the G-Code software for free from this link (The software only runs on windows). Once you have set it up, engraving on uneven surfaces is just a matter of following these easy steps;

  • Open the file in the G-Code ripper application
  • Enable splitting of the image by marking the “mid-center” of the image. You can achieve this by setting the split angle to 90 degrees
  • Rotate the black cuts to 180 degrees by selecting the “rotate black” setting and then save the “black” and “white” g-code files
  • Prepare your laser engraving machine and material
  • Engrave the first of the two images (black and white) that you had generated earlier. The order doesn’t matter.
  • Unmount the piece from the engraving table and rotate it 180 degrees from your original orientation
  • Engrave the second image that you generated earlier

If you have any issues in setting up your software, you can refer to the official documentation of the software which you can access via this link.

Using a Three-Axis Laser Engraver

Laser engraving machines can engrave not just flat materials, but also curved and irregularly shaped objects. It’s so simple to engrave designs on any curved surface with a laser engraving machine!

Laser engravers come in 2-axis, 3-axis and 4-axis configurations. As the number of axis increases, so does the machine’s ability to do complex operations, raising the machine’s price. Even on 2-axis laser machines, an axis (X or Y) can be converted into a rotary axis (A-axis) with an optional rotary upgrade. It also raises the price of the machine.

Two-axis laser engravers have two operational axis (X and Y). It is the most popular and least expensive alternative for laser engravers. The addition of a Z-axis results in a three-axis laser cutter with auto-focus capability since it can independently move the laser module up and down along the Z-axis.

Consider adding a rotary device to your engraving machine if you want to easily engrave round objects like mugs, glasses, tumblers and wine bottles etc. As it engraves over the curved surface of the object, the laser engraver with rotary attachment automatically turns your object. Both the Chuck Style Rotary Axis and the Roller Style Rotary Axis are optional additions for most types of lasers.

Rotary Device
Chuck Style Rotary Device

CO2, Diode laser and Fiber Laser Engraver equipment can have two or three axis. The auto-focus feature in 3-axis machines moves the laser module along the Z-axis automatically.

For a detailed review on the xTool with Rotary - The Best 10W Diode Laser Lasers
For Fiber Laser Engravers including a Rotary or as an add on - The Best Fiber Laser Engraver for you
For CO2 Laser Engravers including a Rotary or an an add on - The Best Laser Engravers Under $5000

The Roller rotary is ideal for both conventional cylindrical objects like drinking glasses, wine glasses, and bottles as well as irregular shaped objects. Normally a roller rotary can only engrave standard cylinders, but the RA2 Pro can engrave irregular and extra-long cylindrical shapes thanks to the separate level tool.

Conclusion

You can use any of the ways mentioned above to successfully engrave on uneven surfaces but if you have a 3 Axis Laser Engraver then engraving on uneven surfaces will become very simple. You cannot get all the functionality you require from a standard laser engraver without a rotary attachment. This is an incredibly handy attachment that will make your life a whole lot easier!